The present invention relates to an electro-optical display containing an electrochromic material held between two electrode carrying support plates and manifesting reversible variations in light absorption properties upon application of a properly controlled voltage or current. This display is referred to as an "electrochromic display (ECD)" hereinafter.
The present invention relates, more particularly, to lead-in electrode structures connected to segment electrodes in the electrochromic display (ECD) of the segmented type.
It was well known that ECDs comprise a pair of substrates, at least one of which was transparent, a desired number of display electrodes formed on the transparent substrate, an electrochromic material film formed on the display electrodes, a counter electrode formed on at least one of the pair of substrates, and a liquid electrolyte disposed between the pair of substrates.
In such an ECD, it was preferable that the area of each of the electrochromic segments and the resistance of each lead-in electrode associated therewith be provided so that their multiplied results were approximately constant. Even when variation in their results was present, it was preferable that these variations be held within about a 10% variation. This situation still holds true at the present time.
A conventional lead-in electrode resistance controlling technique was disclosed in Hiroshi Hamada et al, U.S. Pat. No. 4,153,344, issued May 8, 1979 and assigned to the present assignee, entitled "LEAD-IN ELECTRODE STRUCTURE FOR ELECTROCHROMIC DISPLAYS OF THE SEGMENTED TYPE".
By the conventional lead-in electrode resistance controlling technique as disclosed in U.S. Pat. No. 4,153,344, however, the resistance value was changed by a method of trial and error, in particular, by amending the entire area of the lead-in electrode with the object to make the above-described multiplied results constant. Accordingly, it was not suitable for mass production.
Therefore, it is desirable to vary the resistance of the lead-in electrodes by improved techniques suitable for mass production.